Multi-layer plastic articles are often used as containers to hold, food, beverages, pharmaceuticals, and nutraceuticals. Some multi-layer plastic articles are commonly made from materials such as polyethylene (PET) and polypropylene (PP). Articles made from PET and PP resist environmental degradation, and are reasonably durable, watertight, and economically produced. However, plastic materials such as PET and PP are gas (e.g., oxygen, nitrogen, etc.) permeable. For applications in which gas permeability is undesirable, for example, containers for food products, medicines and products that degrade upon gas permeation into or out of the container, a plastic article of PET or PP may include an interior layer of a barrier material or a gas scavenger material, such as ethylene vinyl alcohol (EVOH), between skin layers of PET or PP.
Molded plastic articles, such as containers for food, beverages, pharmaceuticals, nutraceuticals, etc., often have an open end used to fill the container with product. Some containers for single serve coffee machines have a multi-layer plastic body including an open top portion through which the container is filled with ground coffee. These coffee containers may also include one or more smaller apertures in a bottom portion through which brewed coffee is dispensed. These coffee containers are conventionally formed by first thermoforming a plastic body with a wide top portion, aligning the thermoformed body with a mechanical punch, and mechanically punching out the smaller aperture(s) in a bottom portion. The additional separate cutting or punching step increases the complexity of the production process. Further, in applications where the accuracy or precision of the position of the aperture, or of the diameter of the aperture is important, sufficient accuracy or precision may be difficult to achieve with a punch process or a cutting process. Further, an aperture formed by a punch process may expose an interior layer of the article to the environment.
A mold cavity with one or more aperture-forming regions can be used to create one or more apertures in an injection-molded article. However, when forming a multilayer co-injection molded article with one or more molded apertures disposed between a gate region and a peripheral region of the multilayer article, generally speaking, each aperture-forming region of the mold cavity disturbs the flow pattern resulting in a large gap in interior layer coverage downstream of each molded aperture.